13474 research outputs found
Sort by
Alumina ceramic membrane incorporated with graphene oxide frameworks for protein recovery / Noor Fauziyah Ishak
Get PDFAlumina ceramic membrane is undergoing rapid development and innovation for protein recovery process. However, the limitation of this membrane type is membrane fouling due to the deposition and adsorption of proteins on the surface and pore walls of the membranes. It is crucial to minimize membrane fouling by reducing interactions between protein and the membrane surface via surface modification technique. Thus, the main objective of this research is to develop an alumina membrane with enhanced antifouling property for protein recovery process. An alumina dope consisting of 57 wt.% alumina loading was used to fabricate two alumina membrane configurations; which are flat-sheet alumina (FSA) and hollow fibre alumina (HFA) membranes, via phase-inversion and sintering method. The FSA membrane was prepared through parametric study by optimizing the fabrication parameters which are the blade gap and sintering temperature. With the use of a blade gap of 1 mm and sintering temperature of 1500°C, it was possible to produce an FSA membrane with the highest flexure strength of 697 MPa and a pure water flux (PWF) of 1716 L/m2 .h and peak diameter for pore size distribution of 0.14μm. Meanwhile, the HFA membrane prepared for this study has a PWF of 242.63 ± 24 L/m2 .h, flexure strength of 156 ± 25MPa, contact angle of 29 ± 6°, surface roughness of 59.69nm and peak diameter for pore size distribution of 0.182μm. For the performance of protein recovery, FSA and HFA membranes have a low value of 35 ± 5% and 63.58 ± 0.5% respectively. In addition, the flux recovery rates (FRR) for FSA and HFA membranes were 25.32% and 63.37% respectively. Next, the surface of these membranes was further modified using graphene oxide frameworks (GOFs) as modifier agents to form a selective layer on alumina support. Three different concentrations of GOF(EDA) film was prepared for FSA membrane, and the lowest GO concentration of 5ppm which was 5GOF(EDA)/FSA composite membrane, had the highest PWF of 38.6 ± 1.1L/m2 .h. It also had a BSA recovery of 55 ± 6% at FRR of 46 ± 3% and the membrane pore size of 0.12 µm. In contrast, the HFA membrane had three composite membranes with different diamine monomers which are ethylenediamine (EDA), butylenediamide (BDA) and phenylenediamine (PDA). Among the composite membranes, the GOF(BDA)/HFA exhibited the highest PWF of 10 ± 0.6 L/m2 .h and flexure strength of 197.58 ± 12 MPa. For protein recovery, this composite membrane also exhibited the highest recovery rate among other modified membranes which are 98.40, 98.32, 95.82 and 95.65% for bovine serum albumin (BSA), egg albumin (EA), trypsin (TR) dan lysozyme (LSZ) protein respectively. Furthermore, the FRR and Rt result also suggest that GOF(BDA)/HFA composite membrane had better antifouling properties as it has the highest FRR and lowest total fouling ratio (Rt) of 94.86 % and 21.70 %, respectively for a total of 72h filtration time. As a conclusion, both surfaces modified with FSA and HFA membrane using GOF exhibited better performance in protein recovery application due to antifouling properties
Hybrid passive control system for seismic response mitigation of steel frame structures / Mohammad Hossein Mehrabi
Get PDFLarge vibration forces such as from seismic excitations can cause structural damage and
structural collapse in the case of intense earthquakes. A large number of novel methods and
of these techniques has weaknesses and strengths. Several control devices demonstrate a
two-step mechanism in which the structure's stiffness is initially raised, and then the
of the first vibration period down to a region where the structural response is significantly
increased. The main aim of this thesis is to propose a hybrid passive control system
comprises of two phases for the seismic retrofit of moment-resisting steel frames. The first
phase is a viscoelastic device called Rotary Rubber Brace Damper (RRBD), consisting of
five steel plates and four layers of rubber. The second phase is a cable bracing system
bundled with a pre-compressed spring (PCS). The transition between these two phases
consists of an increasing stiffness as the system transitions from the viscoelastic RRBD to
the cable bracing PCS. In order to develop and prove the effectiveness of the hybrid passive
control system, this research is divided into two parts. The first part includes the
characterization of rubber compounds and analytical modeling of the RRBD concept with
the aim of ABAQUS software. Then, experimental testing was conducted to determine the
material properties of the rubber compounds, and, finally, the most promising rubber
compounds were selected for possible inclusion in the device. The RRBD functioned at
early stages of lateral displacement, indicating that the system is effective for all levels of
strategies for seismic retrofitting have been developed and successfully implemented. Any
dissipation energy phase is engaged upon yielding of the device. This may result in a shift vibration. The second part of this research focuses on the PCS system. Both experimental
and analytical studies were conducted, and no loosening in the cable is observed, as the
cables are held in tension by the spring's force; thus, the ability of the bracing system to
cause impulses is eliminated. A PCS system design procedure was developed through
analytical and experimental testing and then it was used for practical implementation of the
proposed system. The overall behavior of the hybrid system during testing demonstrates
multi-phased behavior with the capability for energy dissipation at all deformation levels
and significant energy dissipation for seismic events. It shows that the proposed hybrid
system creates a unique and innovative method which enhances the strengths and offsets
the weaknesses of the individual systems
Evaluation of antitrypanosomal activity of bisindole alkaloid, ochrolifuanine from Dyera costulata (Miq.) Hook.f / Norhayati Ismail
Get PDFHuman African Trypanosomiasis (HAT) is a neglected tropical disease which can be fatal if left untreated. The search has been ongoing to explore additional or alternative remedies from natural products which have great potential to treat the disease since current drugs treatment are very limited due to resistance and side effects to patients. The aim of this study was to search for potential antitrypanosomal compound candidate
from Dyera costulata (Miq.) Hook.f (locally known as jelutong) leaves. In this study, an antitrypanosomal active compound was isolated from the active methanolic extract of D. costulata leaves by using bioassay-guided isolation and chromatographic techniques. The compound identified as bisindole alkaloid ochrolifuanine using Nuclear Magnetic Resonance (NMR) and Mass Spectrum (MS) as well as by comparison with reported data. The in vitro inhibitory activity of extract and fraction samples against Trypanosoma brucei brucei strain BS221 was tested using Alamar Blue assay. Ochrolifuanine showed potent antitrypanosomal activity with IC50 value 0.05 ± 0.01 μg/ml and high selectivity towards the trypanosome cells (Selectivity Index, SI = 52). Since apoptosis plays an important role in cell density regulation in the parasite, the effect of ochrolifuanine in apoptosis induction was investigated. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay was used to observe the effect of ochrolifuanine on apoptotic DNA fragmentation in T. b. Brucei cells treated with ochrolifuanine. Ochrolifuanine was shown to induce an apoptotic DNA fragmentation in trypanosome cells in a dose- and time-dependent manner. Trypanosome cells treated with 0.05 μg/ml concentration of ochrolifuanine exhibited early apoptosis and more than 50% apoptotic cells were detected in as early as 6 hours of incubation. Additional study on measurement of DNA content in trypanosome parasites was carried out using flow cytometry. In 24 hour observations, treatment of cells with 0.025 and 0.05 μg/ml of ochrolifuanine arrested the growth of T. b. brucei at two different phases (G0/G1 and in S phases). While at the highest dose treatment of 0.10 μg/ml of ochrolifuanine, blockage of cell progression at the G2/M phase in T. b. brucei cell cycle was observed. These results demonstrated that ochrolifuanine displayed strong antitrypanosomal effect on T. b. brucei by inducing apoptosis and causing arrest of parasite cells at different growth phases. This study reports for the first time on the antitrypanosomal activity of ochrolifuanine from D. costulata leaves. Hence, ochrolifuanine is a potential candidate for the discovery of novel therapeutic drugs to treat trypanosomiasis disease
Indirect focused written corrective feedback on elementary ESL learners’ writing / Sim Chiang Huey
Get PDFThis study investigates the efficacy of indirect focused written corrective feedback (IFWCF) on simple past tense errors of two distinct groups of elementary ESL pupils (high and low proficiency level) through a 6-week intervention. Comparison between pretest and posttest was made within groups using paired sample t-test and between groups with Mann-Whitney U test. Based on the findings, the intended measure was effective for the high proficiency group but not the low proficiency group, yet no significant difference was observed between those two groups. Semi-structured interviews were also conducted with ten selected participants with the most significant difference in their pretest and posttest scores to probe their perceptions towards the usefulness of the measure towards their use of simple past tense in their descriptive writing. From the thematic analysis conducted, four major themes were identified. It was revealed that the intended measure was effective in cultivating error identification ability, promoting critical thinking skills, regulating problem solving skills and improving implicit knowledge. Due to the limited sample size, generalization cannot be made upon the population outside the study
Constructing masculinity: A study on three community colorguard troupes in Kuala Lumpur / Syed Khairuzman Syed Zain
Get PDFThis research focuses on the construction of masculinity within three community colorguard troupes in Kuala Lumpur. Colorguard has existed since the early days during the Civil War, where a military band would accompany soldiers on the battlefield. The color guard, or flag-bearer, would also march in battle with soldiers, carrying the “colors” that represents a particular nation. Flags and banners have been used by armies in battle to serve this purpose. As the years passed, colorguards became more correlated with marching bands. In a marching band, the colorguard is a non-musical section where the performers carry equipment such as flags and mock rifles made out of wood. The colorguard provides additional visual aspects to the overall performance, where the colors of the flags accompany and support the music in adding a layer of visual effect. In the United States, the modern colorguard activity is performed by males and females, incorporating dance such as ballet, jazz, modern, or interpretative dance while handling equipment such as flags, rifles, and sabers. In Malaysia, there are two types of colorguards, the female-dominated colorguards in high school marching bands, and community colorguard troupes consisting of majority males that performs without the accompaniment of a marching band. The practice of colorguards in high school marching bands, consisting of flag bearers with more elegant and feminized movements, is dominated by females. Community colorguard troupes, on the other hand, consist of predominantly male performers who use their advantage in physical strength to handle the equipment, such as rifles and sabers that were non-existent in high school marching bands. This ethnographic research examines three community colorguard troupes situated in Kuala Lumpur and how they construct masculinity within their performances. The first troupe is Guards Conspiracy, an all-male colorguard group. The second troupe is Vortex Winterguard, a mix-gendered group with majority males, and the third group is the Batteryheadz Colorguard Ensemble, an equally mix-gendered group. This research examines the construction of masculinity in colorguard that challenges the stigma of dancing being associated with femininity. This dissertation interrogates how masculinity is being constructed, performed, and asserted by men. This research offers a new perspective on masculinity within the field of dance in Malaysia
Effect of different irradiance levels on bioelectricity generation from algal biophotovoltaic devices / Thong Cheng Han
Get PDFPhotosynthesizing organisms including microalgae are exposed to varying levels of light irradiance throughout the day, thus sparking strong research interests in determining the effects of different irradiance levels on the efficiency of biophotovoltaic (BPV) platforms in generating bioelectricity. When light energy strikes the surface of the photosynthetic apparatus of algal cells, electrons are shuttled from the algal cells to the anode through a mediator but scientific findings have suggested that direct electron transfer from the microalgae to the anode could boost the efficiency of electron transport mechanism in a BPV device by reducing internal resistance (Ng et al., 2014a). In this study, mediator less anodes were adopted in the BPV devices by growing algal biofilms from suspension and immobilized Chlorella sp. (UMACC 313) cultures on ITO-coated glass anodes. Immobilized cultures were prepared by entrapping the microalgal cells in 2% sodium alginate solution. The BPV devices were illuminated by four different irradiance levels (30, 90, 150 and 210 µmol photons m-2 s-1 ) to investigate the relationship between varying irradiance levels on the power output of the devices. Photosynthetic performance of the microalgal cells was evaluated using Pulse Amplitude Modulation Fluorometer (PAM) on Days 0, 4, 8 and 12 of the experiment whereas power output of the BPV devices were found from polarization curves generated by applying external resistance stepping technique (Ng et al., 2017). The maximum power density and maximum current density were produced from alginate-immobilized biofilms at the irradiance level of 150 µmol photons m-2 s-1 . High Non-Photochemical Quenching (NPQ) readings at 150 µmol photons m-2 s-1 indicated effective photoprotection in Photosystem II (PS II) that prevents inactivitation of PS II when exposed to strong irradiance. Thelowest power output from immobilized cultures was recorded at 210 µmol photons m-2 s-1 , thus suggesting that partialphotoinhibition had occurred at high irradiance leve
Morphology and genetic characterization of amnesic shellfish toxin producing diatom species, Pseudo-nitzschia and Nitzschia (Bacillariophyceae) in Malaysian waters / Tan Suh Nih
Get PDFDiatom Pseudo-nitzschia and Nitzschia are widely distributed in brackish and marine environments. Some species are known to produce the neurotoxin domoic acid (DA) that responsible for Amnesic Shellfish Poisoning (ASP) in humans and marine organism. While several species have been reported to be toxic in Malaysian waters, there was no confirmed ASP case reported thus far. In this study, samplings were conducted throughout the coastal and mangrove waters of Malaysia to determine the occurrence, distribution and toxicity of Pseudo-nitzschia and Nitzschia species. A total of 548 strains of Pseudo-nitzschia and Nitzschia were established and identified by light and electron microscopy; they are P. batesiana, P. bipertita, P. brasiliana, P. circumpora, P. cuspidata, P. fukuyoi, P. pungens, and N. navis-varingica. Species identification in Pseudo-nitzschia based sorely on morphological characters is challenging owing to the minute morphological differences. Thus, molecular characterization has become an essential supporting criterion in species delineation. In this study, the phylogenetic relationships of Pseudo-nitzschia species were inferred based on three genetic markers. A pair of genus-specific primer targeting cox1 gene were developed in silico. The results revealed three distinct clades in the P. pseudodelicatissima complex, while the P. delicatissima complex formed a distinct clade (Group IV) in both the LSU and ITS2 phylogeny. ITS2 dataset resulted in the most resolved trees, followed by cox1 and LSU. For the benthic diatom Nitzschia navis-varingica, it was found widely distributed in the brackish mangrove areas of Malaysia. To examine the potential ontamination of DA in the local shellfish industry, both the N. navis-varingica strains and shellfish collected were analyzed by FMOC-LC-FLD and LC-MS/MS. DA and its geometrical isomers, isodomoic A and B, were detected in 48 strains of N. navis varingica. Their cellular DA content ranged from 0.37–11.06 pg/cell. For the 25 shellfish samples analyzed, only two cockle samples from Asajaya, Sarawak were detected with 283.72 and 465.04 µg/kg, respectively. To understand the population dynamics of N. navis-varingica in the Western Pacific, the genetic diversity was investigated using LSU rDNA and ITS2 markers. The LSU dataset revealed high sequence homogeneity among all strains examined (0–0.9%). The ITS2 inferences identified eight distinct clades, with high sequence heterogeneity (0.5–19.7%); analysis of haplotype diversity recovered 44 haplotypes. Our results
showed strong gene flow among N. navis-varingica populations in the Western Pacific region (ФST=0.48095). However, isolates from Vietnam and Japan formed a distinct haplotype H3 (FST, 0.41–1.00), suggesting possible genetic structuring between the water bodies of northwestern Pacific and the South China Sea (SCS). It is speculated that ocean current circulations (SCS and Kuroshiro currents) may play a role in this allopatric differentiation of N. navis-varingica. This study has demonstrated the occurrence and wide distribution of the toxigenic Pseudo-nitzschia species and N. navis-varingica in Malaysian waters. The potential ASP risk of in Malaysia should be assessed continuously by monitoring the toxic plankton and level of DA in shellfish mollusks to safeguard public health and ensure seafood safety
Pemakaian fiqh al-Shafi‘i dalam isu-isu makanan halal di Malaysia: Analisis dari perspektif Maqasid al-Shariah / Tuan Sidek Tuan Muda
Get PDFMazhab al-Shafi‘i adalah mazhab utama yang menjadi asas kepada pelbagai penetapan hukum syarak dalam urusan pentadbiran dan pengurusan agama di Malaysia. Perkembangan sains dan teknologi serta pengaruh globalisasi telah memberikan kesan kepada pemakaian mazhab ini dalam penetapan makanan halal dan pengurusan pensjilannya. Pemakaiannya pada sesetengah hukum dianggap ketat serta tidak seiring dengan keperluan perubahan zaman. Sehubungan dengan itu, terdapat cadangan supaya digunakan pendapat fiqh mazhab lain yang dilihat lebih menepati perkembangan semasa dan maqasid al-shari‘ah. Walau bagaimanapun, Imam al-Shafi‘i dan para pendokongnya adalah pelopor kepada ilmu maqasid al-shari‘ah. Sehubungan dengan itu, kajian ini dibuat untuk menganalisis pemakaian fiqh al-Shafi‘i dalam isu-isu makanan halal di Malaysia menurut perspektif maqasid al-shari‘ah bagi menilai sejauh mana kesesuaian pemakaian fiqh al-Shafi‘i dalam penetapan makanan halal seiring dengan perkembangan semasa. Fokus kajian ini ialah isu-isu fiqh yang masih menimbulkan percanggahan pandangan dalam kalangan fuqaha dan memberi kesan kepada perbezaan pandangan hukum, fatwa dan prosedur pensijilan halal. Kajian ini dibuat menggunakan kaedah kualitatif. Pengumpulan data menggunakan kaedah perpustakaan melalui analisis dokumen dan temu bual. Analisis data pula menggunakan pendekatan induktif, deduktif dan komparatif. Hasil kajian menunjukkan bahawa metode fiqh al-Shafi‘i sesuai dan mampu diguna pakai dalam penetapan pelbagai hukum seiring dengan perkembangan sains dan teknologi. Pemakaiannya dalam industri halal semasa dan setempat dengan kaedah yang betul dan terarah menjadikan penetapan hukum makanan halal tidak rigid bahkan mampu mencapai maqasid al-shari‘ah terutamanya dalam pemeliharaan terhadap al-daruriyyat al-khams melalui pendekatan kesederhanaan antara ifrat dan tafrit. Melalui analisis terhadap prosedur, standard dan pandangan hukum makanan halal di Malaysia, didapati wujud unsur-unsur ihtiyat, taysir dan meraikan khilaf. Hasil kajian juga menunjukkan fiqh al-Shafi‘i mampu dijadikan asas kepada standard pensijilan halal global dan seterusnya dapat mengangkat tingkat pelaksanaan pensijilan halal ke tahap yang lebih diyakini
Space-time conceptualizations among Malaysian Chinese bilinguals / David Mahlum
Get PDFA questionnaire and experiment were conducted to investigate whether there is evidence for linguistic relativity among the Malaysian Chinese population. In order to make the influence of language on thought measurable, this study used the principles of conceptual metaphor theory and the conceptual domains of SPACE and TIME. The research aimed to detect the degree to which participants’ conceptualizations of time were conditioned by space-to-time metaphors (STMs) in their primary language (English and Mandarin). A psycholinguistic experiment conducted designed after Fuhrman et. al. 2011 to accomplish this aim. Analysis of the results reveal no influence of STMs on conceptualization of time. Rather, the data revealed bias in a direction opposite of what was predicted. It is concluded that the findings of the current study run counter to the claims of linguistic relativity. More accurate knowledge of the usage of STMs in English and Mandarin is needed as well as more empirical research isolating the influence of STMs on conceptualizations of time
Phytochemical studies and bioactivity evaluation (DENV-2 NS2B/NS3 protease) of Beilschmiedia glabra and Endiandra kingiana (Lauraceae) / Syazreen Nadia Sulaiman
Get PDFPreliminary survey of the dichloromethane crude extracts of two Lauraceae species (Beilschmiedia glabra and Endiandra kingiana) showed moderate dengue inhibition against dengue type 2 NS2B/NS3 protease with percentage of inhibition by 51.28 ± 13.9% and 65.05 ± 3.7%, respectively. Isolation and purification on the active extracts of the B. glabra and E. kingiana yielded seventeen compounds. B. glabra gave nine compounds; 123, 124, 125, 126, 127, 128, 129, 130, and 131. Among nine compounds, 130, and 131 were identified as new neolignans which features a rare oxetane moiety in the structure. Meanwhile, E. kingiana afforded eight compounds; 132, 133, 134, 135, 136, 137, 138 and 139, with 136 identified as a new benzofuran. Their structures were elucidated by spectroscopic techniques such as 1D and 2D NMR, UV, IR, LCMS-IT-TOF and comparison with the literature values. All isolated compounds which of had sufficient amount were tested for inhibitory activity against dengue type 2 NS2B/NS3 protease. From B. glabra, two compounds, 125 and 130 were tested which showed weak inhibition with percentage inhibition less than 50% towards the dengue type 2 NS2B/NS3 protease. As for E. kingiana, five compounds, 134, 135, 136, 137, and 138 were also subjected to in vitro test against NS2B/NS3 protease of DENV-2 where 136 (61.23 ± 7.0%), 137 (69.93 ± 3.3%), and 138 (62.02 ± 6.2%) showed moderate activity with percentage inhibition more than 50%, while the remaining two compounds showed weak inhibition. Therefore, three compounds (136, 137 and 138) with percentage of inhibition more than 50%; were further evaluated in order to determine their respective IC50 values. Compound 137 had a higher potency with a lower IC50 value compared to the other active compounds towards the protease. Then these three active compounds, 136 (IC50 = 403.14 ± 33.03), 137 (IC50 = 170.10 ± 5.94), and 138 (IC50 = 184.13 ± 2.11) were subjected to molecular docking studies to provide much clear picture of the site at which the active compounds bind to the protease. Based on molecular docking studies, 136, 137, and 138 showed common hydrogen bonding interactions with the oxygen atom in each compound with Asn152 at S2 pocket of DENV-2 NS2B/NS3 protease. However, that was the only similar interactions between these three active compounds. For compound 137 and 138, both showed similar interaction with Asp129 and Tyr161 of the DENV-2 NS2B/NS3 protease at S1 pocket, however with different type of bonding as 137 having hydrogen bonding while 138 havin